Frequency and Antimicrobial Susceptibility of Haemophilus influenzae Type b Isolated from Children Suspected to Meningitis

Abstract

Background: Haemophilus influenzae type b (Hib) has emerged as the predominant cause of meningitis in developing coun­tries wherever it has been studied using good microbiologic procedures, but data  regarding frequency, antimicrobial sus­ceptibility and preferable method for detection of Haemophilus influenzae type b isolated from  Iranian patients  were scarce.
Methods: One thousand and eight hundred suspicious CSF samples were received from Children Medical Center Hospital in Tehran, periodically. All samples were cultured on conventional and selective media for Haemophilus influenzae type b de­tection. PCR performed for samples were Hib negative in culture. The susceptibility of the isolates to different an­timicrobial agents was determined using the disk diffusion method.
Results: Overall, 6.7% (n= 121) of specimens had positive culture. 15.7% (n= 19) of isolates were diagnosed as Hae­mophilus influenzae type b with both culture and Antiserum test. PCR assay detected 10 isolates of H. influenzae type b in sam­ples weren't detected in culture. H. influenzae type b isolates were resistance to ampicillin (42.1%), chloramphenicol (36.8%), and co-trimoxazole (52.6%), respectively. The range of antimicrobial susceptibility to cephalosporins was from 52.6% for cephalothin to 57.8% for ceftriaxone, ceftazidime, cefixime and ceftizoxime. Multidrug resistances were ob­served in 31.5% of H. influenzae type b isolates.
Conclusion: Although we found high frequency of resistance to the first line drugs for H. influenzae type b in Iran, but the fre­quency of this organism among children meningitis was lower than many Asian and European countries. PCR assay was more sensitive in detection of H. influenzae than culture method.